feat: add relay to the docs (#103)

Author: MakMuftic

docs/docs/01-introduction/04-supported-networks.md

@@ -15,6 +15,7 @@ New routes, networks, and tokens can readily be added by the Sprinter team. Plea
 - [LI.FI](https://li.fi/)
 - [Across](https://across.to/)
 - [Sygma](https://buildwithsygma.com)
+- [Relay](https://relay.link/)
 
 ### Supported Networks and Tokens